獐子岛附近海域沉积物中氮和磷的分布来源及污染风险评价

【目的】为探讨北黄海獐子岛附近海域氮、磷的来源及其污染风险状况,对该海域表层沉积物中氮、磷的形态和分布特征进行分析。【方法】采用K2S2O8氧化法和HCl浸取法对獐子岛附近海域13个站位的表层沉积物中总氮(TN)、总磷(TP)及其无机和有机态的含量进行分析,并采用单因子标准指数法对氮、磷的污染水平进行评价。【结果】獐子岛附近海域沉积物中TN和TP的含量分别为0.192~1.357 mg/g和0.302~0.489mg/g,有机氮(ON)和无机磷(IP)是表层沉积物中氮和磷的主要存在形式,分别占TN与TP的90.93%和82.84%。沉积物中TN和TP在研究区域南部含量较高,这与沉积物粒度密切相关;而ON、有机磷(OP)两者都与有机碳(TOC)含量具有显著相关性,说明它们具有相似的来源。单因子标准指数法分析表明獐子岛附近海域沉积物中TP含量较低,标准指数均小于1;而TN含量相对较高,其标准指数为0.35~2.47。【结论】獐子岛附近海域沉积物中氮为陆源和自生混合来源,而磷主要是陆源输入;海域沉积物环境受到氮的污染。

Distribution,Source and Pollution Risk Assessment of Nitrogen and Phosphorus in Sediments of the Zhangzi Island,the North Yellow Sea

[Objective] To evaluate the source and pollution risks of nitrogen and phosphorus in the Zhangzi Island area,the North yellow sea,their speciation and distributions of nitrogen and phosphorus in surface sediments were analyzed.[Methods] The contents of total nitrogen (TN) and total phosphorus (TN) with their speciation in 13 surface sediments of the Zhangzi Island were studied by K₂S₂O₈ oxidation and HCl extraction.[Results] Results suggested that TN and TP contents ranged from 0.192 to 1.357 mg/g and 0.302 to 0.489 mg/g,respectively. Organic nitrogen (ON) and inorganic phosphorus (IP) were the main forms,accounting for 90.93% and 82.84% of TN and TP,respectively. The higher TN and TP contents appeared at the south region of the study area,which was closely related to grain sizes. ON and organic phosphorus (OP) had significant correlations with total organic carbon (TOC),suggesting that they are from the similar sources. Single factor contaminant index method indicated that all the single standard indexes of total P (S_p) were below 1 whereas single standard indexes of total N (S_N) ranged from 0.35~2.47.[Conclusion] Nitrogen source in sediments of the Zhangzi Island was from the mixture of terrigenous and marine autogenic sources,whereas phosphorus was mainly from terrigenous sources. The sediments of Zhangzi Island was polluted by nitrogen.